Pulp board.



PATENTED OCT. 3,.1905.

C. SHEPHERD. PULP BOARD. 7 APPLICATION FILED we. 18,1904.

UNITED STATES CHARLES SHEPHERD, OF NEW YORK, N.

PULP BOARD.

Specification of Letters Patent.

Patented Oct. 3, 1905.

Application filed August 18, 1904. I Serial No. 221,192.

To all whom, it may concern..-

Be it known that I, CuAnLns SHEPHERD, a subject of the King of Great Britain, and a resident of the city of New York, borough of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Pulp Boards, of which the following is a specification.

The objects of my invention are to so utilize and to so treat wood-pulp as to obtain a product which may be used as a substitute principally for wood and which may be made up into boards to be used especially in places where it is important to prevent the same from warping and where it is desired to shape and put the same in place by tools such as are ordinarily used in the shaping and working of wooden boards.

In carrying out my invention I avail myself of the qualities and peculiarities of wood-pulp when compressed, and particularly its porosity, which makes it particularly receptive to resinous substances and which makes its thorough impregnation by such substances possible, and I also avail myself of the quality of paste to become reinforced by being combined with such resinous substances.

The sheets of board which I embody in and convert into my final product contain the pulp of wood produced by freeing suitable wood of its bark, passing it through a grinder so as to reduce it to fiber thoroughly mixed with water which is supplied to the grinder, afterward withdrawing the water from it, preferably by conveying a proper quantity of the pulp to a trough underneath the piston of a hydraulic press and there squeezing out the water, so as to form a sheet of the thickness required. After drying said sheets aproduct is obtained which is comparatively porous and which has no grain running in a particular direction, as is apt to be the case with paper calendered in usual manner.

In the accompanying drawings, forming part of this specification, and wherein corresponding figures of reference refer to corresponding parts, Figure l is a perspective view of a wood-pulp board constructed according to my invention, while Fig. 2 is a crosssection of such a board.

In said drawings, 1010 are sheets of woodpulp so produced and pasted together in a preliminary manner by layers of any ordinary or suitable paste, as 11, which may consist of flour and water, pressure by the hand of the operator or any light pressure being sufficient to so bring said sheets together, after which the body so formed is dried, either in the open air or by artificial heat. I then immerse such body in a heated resinous solution, consisting, for instance, of equal parts of the ceiling-varnish of commerce and benzin, so as to causethe same to enter into the body so formed, so as to penetrate said sheets and the paste joining the same together, and after drying the board so prepared I may shellac the same to further protect it and to give a finish to its surface.

I am aware that it is not new to treat sheets of pulp or of paper by immersingthesame in resinous solutions and afterward pasting or cementing the same together under considerable pressures and also afterward saturating the blocks so formed with tar-varnish; but the products so obtained vary materially from that obtained by me, my product being more homogeneous than the products above referred to, due particularly to the greater porosity of the sheets of wood-pulp which I employ, that permits the heated solution freely to enter into and through the same and to more readily reach and more effectively reinforce the temporary joints between the same, made of paste, as described. Besides, my product not having any grain it is not apt to split, and it can be treated and worked with any of the tools ordinarily used in manufacturing wooden articles. It will better resist the influence of moisture and of heat and any tendency to warp or twist than the paper product above referred to and in general to a greater degree possesses the advantages offered by wood, owing to the fact that it contains largely the same ingredients as wood, it being, however, free from grain and knots and anything that might lead to decay or deterioration.

I prefer to shellac the surfaces of the board invented by me to further protect it and also to improve its appearance, it being understood that in general the surface of my improved board may have imparted to it any improvements and embellishments which wood is capable of receiving.

1 do not wish to confine myself to the details and detail combinations herein set forth, as it will readily be seen that they might be varied materially without departing from the spirit of my invention. Thus instead of employing pulp made from the fiber of wood other similar vegetable fibersuch, for instance, as that obtained from cane-might be i used instead. Besides, any other proper resinous substance or solution that will enter into a body of sheets made of pulp and joined together as describednvhen either heated or cold, under atmospheric pressure, or under greater artificial pressure, may be used. The fiber be fore being formed into sheets may be treated in digesters with suitable chemicals, such as caustic soda, and bleaehed,as is done with woodpulp that is to be employed in the manufacture of paper. Further, instead of forming the pulp into sheets by means of a hydraulic press, as above referred to, it may be so formed by withdrawing part of the liquid by suction and afterward passing the pulp between rollers for the purpose of further freeing it from liquid and reducing it to the thickness desired in similar manner as is now done in preparing wood-pulp for shipment to paper-mills.

My pulp boards are distinguished from boards made of paper and treated with resinous substances not only by the superiority of their quality, as mentioned above, but also by the cheapness and simplicity attending their manufacture, a minimum of machinery being required for producing the same. Further, by the process employed by me I add to the strength of the binding substance interposed between the different sheets of pulp, and therefore to the strength of the entire board, by thoroughly impregnating said bind ing substance or paste simultaneously with the impregnation of the sheets of pulp.

I claim The process herein described of preparing and hardening pulp board, which consists in converting wood into fiber while bringing it in contact with liquid, then freeing the semiliquid pulp of part of its liquid, then forming the pulp into sheets, then drying the same, then pasting the faces of such sheets together while the interior portions of such sheetsare substantially free from resinous and gummy substances notoriginally inherent in the wood,

then impregnating the body so formed with a heated resinous solution, and afterward drying the board.' In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 17th day of August, 1904.

CHARLES SHEPHERD. Vitnesses:

O. L. HoRAoK, JOHX A. CALDWELL. 

